"When Peason took over back in 2008, he said Valeant's high-aspiration goal was to become one of the top 15 pharma companies by the end of 2013," Cramer noted

Peason achieved that goal. However, he did it through a string of rapid fire acquisitions. "They have done sixty deals in the last six years," Cramer noted.

So far that strategy has been very successful.

However, what worries Greenberg is that the company now has a new aspirational target.

"Valeant wants to be among the top five pharma companies by the end of 2016, which would mean more than tripling the company's market cap over the next three years to $150 billion. That is a very ambitious goal, and Herb Greenberg makes it pretty clear that the only way Valeant can even get near there is by doing many more acquisitions, and possibly one big acquisition."

Historically, Greenberg says this is the kind of strategy that almost always ends badly. That is, the deals either dry up or they're not as accretive as they once were or they burden the company with massive debt.

In fact, the acquisition strategy has already generated a lot of debt.

"Herb points out that the company's debt has ballooned from $4.9 billion two years ago up to $17 billion as of last quarter." Even more debt on the balance sheet can't be good.

To make this strategy all the more concerning, Greenberg reminds that interest rates are rising. "Higher rates make it much more expensive for Valeant to borrow the money it needs to do these deals," Cramer said.

And Greenberg notes that M&A in the sector is accelerating broadly. That likely makes future acquisitions more expensive. Again, a problem.

On top of all that, if the company issues a secondary to pay for the expansion, shareholders will likely be facing significant dilution. That's not good, either.

All told, Greenberg's analysis suggests owning Valeant going forward might be something like a game of hot potato. "When the deals eventually dry up, you do not want to be the one holding this stock."

Cramer agrees with Greenberg. "Even if we end up sitting out a lot of upside in the near-term, I'm telling you, it's just not worth the risk," Cramer said. "I've followed Herb's work for more than 20 years and I never want to be on the wrong side of one of his challenges."